June 1996
Surface Water Supply Index Report

Provided by the US Natural Resources Conservation Service
Bozeman, Montana

The SWSI is designed for areas that rely primarily on snowmelt runoff as the primary source of surface water. The SWSI accounts for snowpack, mountain precipitation, streamflow, reservoir contents, and soil moisture conditions. The SWSI can be used by irrigators, fisheries personnel, recreationists, and others who utilize surface waters. SWSI values are categorized as follows:

IDBasin NameValue
1Marias Above Tiber Reservoir2.9
1Marias Above Tiber Reservoir2.9
2Tobacco3.6
2Tobacco3.6
3Kootenai to Libby Dam3.2
3Kootenai to Libby Dam3.2
4Kootenai River below Libby Dam2.5
4Kootenai River below Libby Dam2.5
5Fisher River2.1
5Fisher River2.1
6Yaak River2.7
6Yaak River2.7
7North FK. Flathead River3.4
7North FK. Flathead River3.4
8Middle FK. Flathead River3
8Middle FK. Flathead River3
9South FK. Flathead River2
9South FK. Flathead River2
10Flathead at Columbia Falls2.8
10Flathead at Columbia Falls2.8
11Stillwater/Whitefish Rivers3.4
11Stillwater/Whitefish Rivers3.4
12Swan River2.9
12Swan River2.9
13Flathead River at Polson2.6
13Flathead River at Polson2.6
14Mission Valley2.1
14Mission Valley2.1
15Little Bitterroot River1.9
15Little Bitterroot River1.9
16Clark above Missoula1.9
16Clark above Missoula1.9
17Blackfoot River2.8
17Blackfoot River2.8
18Clark Fork above Missoula2.4
18Clark Fork above Missoula2.4
19Bitterroot River2.9
19Bitterroot River2.9
20Clark Fork River below Bitterroot River2.9
20Clark Fork River below Bitterroot River2.9
21Clark Fork River below Flathead River2.7
21Clark Fork River below Flathead River2.7
22Beaverhead River1.7
22Beaverhead River1.7
23Ruby River2.4
23Ruby River2.4
24Big Hole River2.9
24Big Hole River2.9
25Boulder River (Jefferson)1.4
25Boulder River (Jefferson)1.4
26Jefferson River2.6
26Jefferson River2.6
27Madison River3
27Madison River3
28Gallatin River3
28Gallatin River3
29Missouri River above Canyon Ferry3
29Missouri River above Canyon Ferry3
30Missouri River below Canyon Ferry2.9
30Missouri River below Canyon Ferry2.9
31Smith River2.1
31Smith River2.1
32Sun River2.6
32Sun River2.6
33Teton River2.6
33Teton River2.6
34Birch/Dupuyer2.3
34Birch/Dupuyer2.3
36Musselshell River2
36Musselshell River2
37Missouri River above Fort Peck3.1
37Missouri River above Fort Peck3.1
38Missouri River below Fort Peck2.4
38Missouri River below Fort Peck2.4
39Milk River2.9
39Milk River2.9
41Yellowstone River above Livingston3.7
41Yellowstone River above Livingston3.7
42Shields River1.7
42Shields River1.7
43Boulder River (Yellowstone)3.5
43Boulder River (Yellowstone)3.5
44Stillwater River3.7
44Stillwater River3.7
45Rock/Red Lodge Creeks3.5
45Rock/Red Lodge Creeks3.5
46Clarks Fork River3.7
46Clarks Fork River3.7
47Yellowstone River above Bighorn River3.6
47Yellowstone River above Bighorn River3.6
48Bighorn River below Bighorn Lake3
48Bighorn River below Bighorn Lake3
49Little Bighorn River1.2
49Little Bighorn River1.2
50Yellowstone River below Bighorn River3.3
50Yellowstone River below Bighorn River3.3
51Tongue River1.1
51Tongue River1.1
52Powder River1.5
52Powder River1.5